What's New in Python 3.12

Post by ddejohn » Wed, Oct 18, 2023, 10:38 PM UTC

wodenokoto wrote: post #56

NoboruWataya wrote: post #34

I suspect people will use these comments to share their wishlist of Python features, so let me add that I really wish Python had a safe navigation operator, for when you are dealing with nested objects that could be None. I have been trying to parse a lot of XML and JSON in Python lately and a feature like that could really help reduce boilerplate checks. https://en.wikipedia.org/wiki/Safe_navigation_operator

def safe_navigation(obj, path: List[str], default=None): try: for key in path: obj = obj[key] return obj except KeyError: return default Yeah. I thought it would just be a try-except, but that turned out pretty ugly. But really, how do you know if your path is missing or the object at the end of the path is None, without using exceptions for communicating this?

Post by samtheprogram » Wed, Oct 18, 2023, 11:18 PM UTC

Post by o11c » Thu, Oct 19, 2023, 12:26 AM UTC

ddejohn wrote: post #102

o11c wrote: post #65

Earlier quoted context omitted.

I would write: def safe_navigation(obj: Any, *path: str, default: Any = None, strict: bool = False) -> Any: sentinel = object() if strict else None for key in path: obj = obj.get(key, sentinel) if obj is sentinel: return default return obj The only new disadvantage of this is that it only works on mappings and no longer works on sequences. But I really don't like having this much `Any`; it's generally a sign of poor…

I wouldn't call a function that mutates the input "safe navigation", personally :)

Post by dmr_92 » Thu, Oct 19, 2023, 1:31 AM UTC

ddejohn wrote: post #101

wodenokoto wrote: post #56

Earlier quoted context omitted.

def safe_navigation(obj, path: List[str], default=None): try: for key in path: obj = obj[key] return obj except KeyError: return default Yeah. I thought it would just be a try-except, but that turned out pretty ugly. But really, how do you know if your path is missing or the object at the end of the path is None, without using exceptions for communicating this?

There's certainly humor in a function called "safe navigation" mutating the data structure I'm supposedly safely navigating through :D

Post by masklinn » Thu, Oct 19, 2023, 4:09 AM UTC

samtheprogram wrote: post #103

> Of note, the distutils package has been removed from the standard library. How is this not a major version change if a module is removed from the standard library? Other breaking changes too. This is confusing to me.